The concept of cellular senescence is based on the notion that proliferation of normal diploid cells can only occur for a limited period of time after which cells slowly cease to divide and die. This limitation of lifespan for in vitro cell cultures was first described by Leonard Hayflick in 1961, going against the theory formulated by Alexis Carrel claiming that cells kept in culture have an unlimited potential for division (Carrel and Ebeling, 1921). Evidence from cell senescence studies have been used to explain the basis of healthy ageing as well as develop food supplements promoting the delay of ageing. Since these discoveries, there has been marked expansion of anti-stress gene response research with relation to the role of the transcription factor NF-E2-related factor-2 as well as healthy ageing with regards to dietary activators intake. This study examined the effects of sulforaphane (SFN) and hesperetin (HESP) on MRC-5 cell senescence in vitro as well as characterized gene expression and cell metabolism in cells escaping senescence by treatment with SFN and HESP and the mechanism of decrease glucose metabolism by SFN and HESP action linked to delay of fibroblast senescence. The effects of treatment of MRC-5 with the dietary bioactivators SFN and HESP was studied and shown to delay cellular senescence in these cells in vitro. Similar findings for SFN treatment of BJ cells were found previously by studies of the host team. Caloric restriction mimetic mechanisms by treatment with 1 μM SFN and 5 μM HESP was shown due to the decrease in culture glucose consumption increase with senescence in these treatment groups and this CR restriction mimetic effect and decrease in the flux of formation of D- and L-lactate in the SFN-treated group was consistent with previous studies done in CR and ageing in mice models (Hargopan, Ramsey and Weindruch, 2003). Moreover, in this study, SFN was shown to act as a CRM dietary bioactive through cellular contents of glycolytic intermediates with SFN-treatment (Bensaad et al., 2006). Finally, the mechanism by which SFN induces delay of senescence through CR was shown to be due to the extraction of Mondo A from the cell nucleus to the cytoplasm.

The formation of embryoid bodies has long been utilized to initiate differentiation of embryonic stem cells in vitro. The embryoid body provides an effective means of recapitulating early stages during embryogenesis and formation of the three germ layers. Current methodology for embryoid formation is extensive but exhibits a lack of standardisation and coherence. Here is shown a 3D culure system for controlled embryonic stem cell aggregation via a non-cytotoxic cell surface modification and cell-cell cross-linking. Embryoid body formation was found to be a complex relationship between embryonic stem cell aggregation, proliferation, death, cluster agglomeration, extracellular matrix deposition and structural reorganisation. Engineered embryoid bodies formed more rapidly and were significantly larger than those in control samples. Embryoid body characterisation revealed a layered internal structure resulting from poor nutrient and gaseous diffusion and consequent core necrosis after ≥ 5 days in suspension culture. Immuno-labelling and PCR amplification analysis of Brachyury, Nestin, Gata-4 and Oct-4 showed differentiation of mesoderm, ectoderm and endoderm on the embryoid body surface and internal undifferentiated cells, respectively. Engineering appeared to enhance mesoderm differentiation, a progenitor of the osteogenic lineage. Embryoid bodies in settled culture spread outwards to form a plateau of collagen matrix which was later mineralized through differentiated osteoblast function. Quantification through Alizarin Red stained bone nodules and alkaline phosphatase activity demonstrated osteogenic differentiation enhancement within engineered samples. Dex-loaded poly-(lactic co-glycolic) acid polymer microparticles were found to be an effective method for delivery of osteo-inductive factors to internal undifferentiated embryonic stem cells within the embryoid bodies. These findings show that the proposed 3D culture system provides reliable and repeatable methodology for the controlled formation of embryoid bodies which exhibit enhanced osteogenic differentiation. It is hoped that these engineered embryoid bodies could be used to efficiently generate homogeneous bone tissue for clinical application.

No description available.

On the Tibetan Plateau, there is a long history of animal farming practices. Although Tibetan pastoralism had been successful in the past to support the population, the problems of increasing demand and impact in the face of more scarce resources and global climate change are challenging pastoralists. The problem is even more pronounced in the Tibetan Plateau’s unique natural and socioeconomic conditions. Based on the perception of the problem, the Chinese government started a reform programme aiming at changing the nomadic practices in Tibet. Tibet today is in transition, not only in terms of pastoralism, but also that of culture, of institutions, and of economy, nevertheless the transition in pastoralism as a livelihood and source of income will have significant implications. The usefulness of the resilience concept in examining a complex system’s innovation, development, disturbance and reorganisation makes them suitable tools in the study of historical changes and the future of Tibet, as the area is under human management, and subject to the influence of changes in nature and external policies. In this study remote sensing and mathematical modelling approaches are used to assess ecological resilience in the region. The advantage of remote sensing allows the researcher to observe and analyse a large area as well as recent changes, and to examine the spatial pattern of these changes. The model simulates the dynamics of the grassland system given the current condition. The key functions linked to the system’s resilience can be examined in this model and provide information on the system’s sustainability. The simulation shows that the nomadic pastoralism system can better adapt to disturbances of known intensity and frequency than the sedentary style. However, the trend of climate change and population increase may require a change of organisation and practices for the system to be sustained.

Natural history collections house immense amounts of data, but the majority of data is only accessible by locating the collection label, which is usually attached to the physical specimen. This method of data retrieval is time consuming and can be very damaging to fragile specimens. Digitizing the collections is the one way to reduce the time and potential damage related to finding the collection objects. The Elm Fork Natural Heritage Museum is a natural history museum located at the University of North Texas and contains collections of both vertebrate and invertebrate taxa, as well as plants. This project designed a collection digitization workflow for Elm Fork by working through digitizing the Benjamin B. Harris Herbarium. The collection was cataloged in Specify 6, a database program designed for natural history collection management. By working through one of the museum’s collections, the project was able to identify and address challenges related to digitizing the museum’s holdings in order to create robust workflows. The project also produced a series of documents explaining common processes in Specify and a data management plan.

Cytochrome family P450 4A encode a major group of enzymes which are involved in the mechanism of peroxisome proliferation in rodents. Induction of CYP4A expression by peroxisome proliferators is due to transcriptional activation, mediated via the peroxisome proliferator activated receptor alpha. Cyp4a enzymes catalyse the w-hydroxylation of fatty acids and eicosanoids, and it has been suggested they thereby play a pivotal role in blood pressure regulation. Murine Cyp4a10, Cyp4a14 and Cyp4a12 genes have been reported by Bell et al (1993) and Heng, et al (1997). There is contradictory evidence in the literature concerning the expression of lauric acid hydroxylase (LAH) and Cyp4a-related protein in mouse liver and kidney. We have previously shown that Cyp4a12 is expressed at high level in a male-specific fashion in liver and kidney of mouse (Bell et al 1993). However, various workers have reported the presence, or absence, of Cyp4a proteins, or LAH, in male mouse liver. Work by Hiratsuka et al (1996) demonstrate that ddY mice show a male specific expression of LAH and Cyp4a-related protein in the liver, while other strains Balb/c and C57BL/6 exhibit no sex difference in neither enzyme or protein. In the kidney, ddY, Balb/c and C57BL/6 all show sexual dimorphism in the expression of both LAH and Cyp4a related protein. The aim of this project was to characterise the expression of mouse Cyp4a12 and resolve the conflicting results in the literature. Findings demonstrate that there is a male specific expression of Cyp4a12 in male liver and kidney. The data differs from Hiratsuka et al in that their findings present no sex difference in Balb/c and C57BL/6 expression of Cyp4a proteins. Hiratsuka et al also determined that in the kidney of ddY, Balb/c and C57BL/6 there is no sex difference in expression of neither enzyme or protein. Data here agrees with these findings and suggests that the sexual dimorphism exhibited by the LAH and Cyp4a related protein in the kidney is due to constitutive expression of Cyp4a12. Thus it appears that there is till a discrepancy between the Cyp4a12 hepatic expression pattern presented here and that of the enzyme and protein determined by Hiratsuka et al. An explanation may infer that the LAH and Cyp4a-related protein measured by Hiratsuka et al is not only Cyp4a12 but also another member of the Cyp4a family. Further work is required to establish what Cyp4a is expressed predominately in the female. Work by Henderson et al (1994) supports the case that this Cyp4a candidate may be Cyp4a10. Continuing studies will clarify the expression pattern of the Cyp4a and also investigate the mechanism of regulation of the Cyp4a family genes and the expression of male specific genes.

Part One Preparations of nucleoprotein having reproducible characteristics were obtained from calf thymus glands by a mild extraction procedure. A preliminary examination of the dissociation of the complex was made and its physico-chemical behaviour was investigated in relation to that of its nueleic acid component. The nucleoprotein was highly aggregated in solution at low ionic strength, but at high ionic strength a weight-average molecular weight lower than that of nucleic acid itself provided additional evidence for the dissociation of the nucleoprotein. Spectrophotometric studies showed that the nucleoprotein was denatured by heat and by alkali in a similar manner to nucleic acid, although denaturation by heat was slightly retarded. The spectrophotometric titration behaviour of the two substances was almost identical, but their potentiometric titration curves differed significantly. Nucleoprotein solutions exhibited the features of nucleic acid devolving from its unique helical structure, indicating that this structure is retained by the nucleic acid within the complex. Part Two A general reaction has been discovered between amino sugars and aldoses for which the essential requirements are a free amino group and an aldehyde group. Three compounds (A, B and C) were separated by ion- exchange chromatography from a mixture obtained by heating D-mannose with D-glucosamine hydrochloride. Compound B was identified as 5-hydroxymethyl furfuraldehyde (HMF) from its ultra-violet absorption spectrum, chromatographic behaviour, and distribution coefficients between two different solvent systems, and was characterised as its 2:4-dinitrophenylhydrazone. Compound A was very unstable and was hydrolysed by cold water to mannose (characterised as its p-nitranilide) and glucosamine (characterised as its carbobenzoxy derivative). On heating in aqueous solution, the hydrolysis was accompanied by degradation to HMF (characterised in the same way as compound B), and the formation of melanoidins. The HMF isolated from the reaction mixture was shown to arise from compound A and C14-HMF was obtained when the condensation was effected with a mixture containing C-mannose and glucosamine hydrochloride, showing that the HMF originated in the mannose moiety of compound A. From these and other experiments, the structure N-mannosyl-glucosamine was assigned to compound A. Compound C was stable in aqueous solution, and hydrolysis with acid gave equimolecular quantities of mannose and glucosamine hydrochloride, but was not accompanied by a browning reaction. On the basis of periodate oxidation experiments, its behaviour in the Elson-Morgan reaction, and a number of other colour tests, compound C was provisionally assigned the structure 6-O-α-D-mannosyl-Z-amino-2-deoxy-D-glucose. Certain aldehydes were found to behave as bases on a sulphonated polystyrene resin. This interesting discovery may provide the basis of a new method for the separation and analysis of aldehyde mixtures.

No description available.

Solid surfaces that spend long periods of time in aquatic environments are susceptible to the accumulation of marine fouling organisms and this phenomenon is known as marine biofouling. This is a natural process which has significant impacts on marine industries. Research to develop new antifouling solutions focuses on the development of non-toxic solutions that can deter biofouling. A non-toxic antifouling approach that has gained interest in recent years is to modify the surface’s structure to disrupt organism settlement (Kirschner and Brennan 2012; Magin et al. 2010; Myan et al. 2013). Many studies determined that uniform arrays of single layered, micro-topographies are effective at deterring the initial settlement of fouling organisms. In contrast, most studies that tested uniform arrays of single layered, macro-topographies concluded that these topographies are not suitable for antifouling applications. Both single layered, micro-topographies and single layered, macro-topographies were determined to have limitations at mitigating biofouling. This resulted in the interest to develop hierarchical topographies. Hierarchical topographies are surfaces that consist of features that are varied in size and shape. It was suggested that the diverse nature of hierarchical topographies might be able to deter biofouling from a wider array of organisms. This research fabricated and tested a wide range of topographies (uniform, non-uniform, micro, macro, hierarchical, etc.) in a field study. A field study was preferred over lab experiments because results will reflect the antifouling efficacy of the surfaces in a marine environment. These results will indicate the topographies’ viability and future potential for industrial applications. Antifouling efficiency was evaluated by measuring fouling resistance (during the field test) and fouling removal (after the field test) of all topographies. Physical attributes (pattern geometry, pattern size, and surface roughness) of topographies were characterised with Scanning Electron Microscopy (SEM) and Laser Scanning Confocal Microscopy (LSCM). Statistical analysis was carried out to evaluate the significance of the topographies’ physical attributes on the antifouling efficiency of the topographies. The research hypotheses predicted that topography size, geometry and surface roughness will affect the topographies’ ability to resist biofouling. All patterned surfaces were predicted to have a higher resistance to biofouling in comparison to un-patterned control surfaces (i.e. smooth surfaces). The possibility that hierarchical topographies would have better fouling resistance properties than micro-topographies was considered as well. Hierarchical topographies and micro-topographies were also hypothesised to demonstrate better resistance to biofouling than macro-topographies. Topographies with straight ridges and hierarchical shapes were predicted to be more fouling resistant than sandpaper surfaces. Topographies with average roughness (RSa) that were less than 100µm were assumed to exhibit better antifouling efficacy in comparison to topographies with average roughness greater than 100µm. Results showed that pattern size and pattern geometry affects the antifouling efficiency of topographies. Unexpectedly, surface roughness did not show strong correlations with the fouling resistance of the topographies. With the exception of Sandpaper 50 and Sandpaper 1mm samples, all topographies were more fouling resistant than the control samples (i.e. smooth surfaces). Among the 16 topographies, sandpaper 1mm samples demonstrated the worst defence against biofouling. The mean total fouling coverage on these samples after 10 weeks of tests was 98.7%. Straight, single layer ridges demonstrated the best resistance to total fouling during the field test. Barnacle and polychaete settlement trends were affected by the size and geometry of single layer, single sized topographies. After 10 weeks, the mean total fouling coverage on these ridges was only 37.5%. The field test also showed that the topography with the best prolonged resistance to fouling was the 1mm straight ridges. The combination of structured surfaces and a low modulus material is likely to have contributed to the fouling removal properties of all topographies. Lastly, results from the field study also showed that hierarchical topographies do not necessarily have better antifouling properties than single layer, single sized topographies. The field study demonstrated that the physical attributes of topographies contributed to their antifouling efficiency. It has been suggested that the physical characteristics of topographies induces hydrodynamic variations that affects the surfaces’ antifouling properties. However, it is difficult to observe these changes in lab experiments or through field studies because these variations take place at a very small scale. Recent research has applied Computational Fluid Dynamics (CFD) to numerically simulate and analyse flow characteristics in the surrounding areas of antifouling topographies. As a continuation from the field study, the next study in this research applied CFD to analyse flow characteristics over several topographies that were tested in the field study. This was to determine if the settlement trends exhibited by organisms in the field study could have been affected by hydrodynamic variations that were induced by the presence of the topographies. The CFD analysis showed that rotational vortices formed between topography patterns. These vortices could have aided in the accumulation of biofouling material on all topographies during the field test. The analysis also showed that the topographies’ resistance to fouling could be attributed to high shear stress and strain rate zones at the peaks of the topographies. Comparisons between CFD and field test results indicate that higher stresses and strain rate zones around the topographies are likely to lead to a surface’s better resistance to marine biofouling. This is likely because high shear stress and strain rate zones could have disrupted organism motility and made the surface less conducive for settlement.

An accurate evaluation of total population density is required in many ecological and biological field. To protect crops from pest attacks, the population density of pests must be evaluated adequately. Accurate information obtained as a result of trapping in ecological monitoring is beneficial for decision-making purposes when implementing a control action. In pest monitoring, a classic technique of evaluating density based on a statistical method may result in poor accuracy. Accuracy can be optimised by applying alternative numerical integration methods to the problem. We explain how insufficient information regarding population density negatively affects the accuracy of estimation. Consequently, a coarse grid problem arises where the numerical integration methods are no longer valid. The evaluation of integration error is now a random variable and the probabilistic approach is used, due to the uncertainty in sampling data. In this thesis several population models have been considered to explain that the value of correlation coefficient on a coarse sampling grid is lost even if the true value is close to one. Phenomenon of ghost synchronization has been observed when the value of correlation coefficient on a coarse sampling grid is close to one but in reality the dynamics are not correlated.